This invention relates generally to commercial refrigeration and more particularly to a commercial refrigeration system having unique power and communication wiring, as well as distribution of control intelligence features.
Great advances have been made over the last 50 years in all aspects of refrigerated food store merchandisers and coolers and the various commercial systems therefor. Retail food merchandising is conducted to a great degree in large supermarkets, each requiring substantial refrigeration capacity. For example, a 50,000 square foot (4,650 square meter) supermarket may have refrigerated display fixtures and other coolers and preparation rooms requiring an aggregate refrigeration capacity in excess of 80 tons (1,000,000 BTU/hr. or 242,000 kcal/hr.) which may include over 20 tons (60,500 kcal/hr.) of low temperature refrigeration at evaporator temperatures in the range of xe2x88x9235xc2x0 F. to xe2x88x925xc2x0 F. (xe2x88x9237xc2x0 C. to xe2x88x9221xc2x0 C.) and over 60 tons (181,500 kcal/hr.) of normal temperature refrigeration at evaporator temperatures in the range of 15xc2x0 F. to 40xc2x0 F. (xe2x88x929xc2x0 C. to 4xc2x0 C.). Such present commercial refrigeration systems have a multitude of evaporator cooling coils for the various refrigerated product merchandisers located throughout the supermarket; and these evaporators are typically cooled by several multiplexed low temperature and medium temperature compressor systems. It is also known to use such systems in smaller environments such as convenience stores, or for the preservation of other perishables not related to the food store environment (e.g., blood, plasma, medical supplies).
Conventional practice is to put the refrigeration requirements of a supermarket into two or more multiplexed refrigeration systems-one for the low temperature refrigeration fixtures for refrigerating fresh foods including meat, dairy and produce at product temperatures in the range of 28xc2x0 F. to 50xc2x0 F. (xe2x88x922xc2x0 C. to 10xc2x0 C.). Each such system is a closed system branch having a single condenser/receiver and common discharge suction and liquid distribution headers with parallel circuits of the latter to the respective merchandiser or cooler evaporators and with the various complex valving requirements to balance suction pressures (EPR valves) and to accommodate selective evaporator isolation for gas or other types of defrosting. In any event, the multiplexed compressors of such systems are usually installed in back machine rooms and typically connect to roof top air-cooled condensers, which in turn connect back to the machine room to a receiver and thence to the liquid refrigerant distribution header and various high side valving and liquid line circuit outlets.
The multiplexed compressors in a refrigeration system are typically mounted together on a rack and piped in parallel, each having a low side connected to a suction header and a high side connected to the discharge header. The operation of the compressors is cycled, based on a measured system parameter, to maintain a desired level of refrigeration. Usually, the measured parameter is suction pressure at the suction header. A transducer on the suction header provides a signal to a compressor controller indicating the suction pressure, and the controller compares the measured pressure with a setpoint pressure and turns the compressors off and on accordingly, taking into consideration other factors such as compressor run time. It is also known to adjust system capacity in other ways, such as by changing the speed of an individual compressor motor where the design of the compressor permits. Refrigeration level can also be affected by cycling condenser fans and in other ways not directly pertaining to the compressors.
In addition to the controller, each compressor has a high voltage protection circuit capable of shutting down the compressor when it operates outside any one of a number of predetermined safe operating limits. A high voltage line in a shielded conduit must be brought from the store utility power distribution center to the compressor where the protection circuit is located. The protection circuit normally energizes a compressor control coil to close a compressor contact in series with the compressor power line so that the compressor may run when activated by a relay operated by the controller. Operating limits are typically established for one or more of: motor winding temperature, oil level (or pressure), discharge pressure and phase loss/reversal. The protection circuit has a safety contact wired in series for each operating limit. When a particular operating limit as detected by a corresponding sensor is exceeded, the contact opens causing the control circuit to open, de-energizing the compressor contactor coil and disabling energization of the compressor by the controller.
Existing protection circuits are aware only that the operating limit has been traversed, and have no capability to provide information as to the actual value of the parameter. A separate alarm circuit from the controller to the control circuit is needed so that notification of the problem can be made. In order to know which operating limit was traversed, still more indicator circuits are required between each safety contact and the controller. Thus, a substantial amount of wiring is necessary to connect the compressor to the controller. Even if the protection circuit is so wired for providing maximum information, there are substantial gaps in information concerning the operation of the compressor because of the absence of the ability to give an absolute reading of the parameter measured.
A parallel switchback circuit may be wired in parallel to the controller so that electro-mechanical control of the compressor can be activated in the event of controller failure. The parallel switchback circuit allows a suction pressure control switch to activate the compressor in the absence of a functioning controller. The switchback circuit provides only crude system control subsequent to controller failure. In order to have such a circuit it will be necessary to install isolation relays to prevent the possibility of control interference from the switchback circuit when the controller is operating normally.
In addition to the control wiring described above, power wiring is also necessary. The compressor is powered by a high voltage, three phase 480 V AC or 208 V AC line (or various other three phase power sources) and the control circuit is powered by a single phase 120 V AC or 208 V AC high voltage line. Two high voltage lines must be wired for each compressor; one three phase for the compressor motor and one single phase line for the protection circuit. These lines are required to be shielded, such as by placement in a conduit. Thus, a number of shielded power lines are required for each compressor rack, making existing wiring complex and costly.
Most of the sensors now used for monitoring safety and control parameters for the compressors are located outside of the compressor. Suction pressure monitoring is typically from the suction header, substantially remote from the compressors. Sensors associated with the safety module are located on the compressor. Thus, all of these items are exposed to potential damage during shipping and installation.
Further, it is also desirable to monitor and/or control other valving, switching circuits, and sensors associated with each refrigeration branch in a typical multiplexed system. For example, it is desirable to monitor actual fixture temperature to ensure that perishable products are being stored at an appropriate temperature to prevent spoilage. In prior art systems, however, a large amount of wiring is required to provide appropriate interfaces between the compressor rack and the various control valves, switches, and sensors in a given system. The wiring is a complex task and the source of frequent system malfunction, particularly for newly installed refrigeration systems. Such wiring requirements include power wiring, which requires additional shielding and protection techniques, including channeling the wiring through protective conduit.
Examples of the such valving, switching circuits, and sensors that have been used in prior art refrigeration systems may be found in several patents which are owned by the assignee of the present invention. For example, Thomas et al., U.S. Pat. No. 5,743,102, the entire disclosure of which is incorporated herein by reference, discloses a system having modular secondary refrigeration. Such system includes a cooling source remote from the refrigeration units that is constructed and arranged for circulating a fluid coolant in heat exchange relationship with the condenser to obtain optimum condensing and efficiency. FIG. 4 of the Thomas et al. patent discloses various valves and flow control mechanisms suitable for use in such a secondary refrigeration system. Schaeffer et al., U.S. Pat. No. 5,440,894, the entire disclosure of which is incorporated herein by reference, discloses a strategic modular commercial refrigeration system in which multiplexed compressors are placed in close proximity to one or more fixtures.
Shapiro, U.S. Pat. No. 6,067,482, the entire disclosure of which is incorporated herein by reference, discloses a load shifting control system for a commercial refrigeration system. As disclosed therein, a processor is configured to select a preferable combination of loads, and to generate control signals so as to achieve an allocation of loads between power sources. FIG. 3 of the Shapiro patent is illustrative of a commercial refrigeration system in accordance with a preferred embodiment of that invention.
Several other patents identify various structures, systems, and methods for defrosting a refrigeration system. Among such patents is Quick, U.S. Pat. No. 3,343,375, the entire disclosure of which is incorporated herein by reference, discloses a latent heat refrigeration defrosting system. In particular, the Quick patent discloses a system for defrosting evaporators using the latent heat of saturated compressed gasses. FIG. 1 of the Quick patent is exemplary of such a system. Further, Behr et al., U.S. Pat. No. 5,921,092, the entire disclosure of which is incorporated herein by reference, discloses a fluid defrost system and method that is suitable for use in secondary refrigeration systems, such at the system disclosed in the Thomas et al. patent, which is discussed above. FIGS. 1 and 2 of the Behr et al. patent are illustrative of aspects of that invention, including the control valves and switching associated with such a system.
Still other patents disclose various structures, systems, and methods related to controlling the oil used in a commercial refrigeration system. Included among these patents is DiCarlo et al., U.S. Pat. No. 4,478,050, the entire disclosure of which is incorporated herein by reference. The DiCarlo et al. patent discloses an oil separation system, including control means for maintaining a predetermined oil level in the compressor. FIG. 1 of the DiCarlo et al. patent is believed to be illustrative of a typical commercial refrigeration system embodying such a system, including the control valves and switches used in the system. A related patent by DiCarlo et al., U.S. Pat. No. 4,503,685, the entire disclosure of which is incorporated herein by reference, discloses an oil control valve, suitable for use in an oil separation and delivery system of a refrigeration system. Yet another related patent by DiCarlo et al., U.S. Pat. No. 4,506,523, the entire disclosure of which is incorporated herein by reference, discloses an oil separator unit, suitable for use in an oil separation and return system of a refrigeration system.
In view of the foregoing, there is a need for a commercial refrigeration system which reduces the need for power wiring between system components. There is a further need for such a system in which subsystem control is distributed among several modules, thereby reducing the risk of failure and the adverse consequences should a failure occur. There still a further need for a commercial refrigeration system that is at least partially self-configuring and is more easily installed and operated, as compared to prior art control systems.
Among the several objects and features of the present invention may be noted the provision of a commercial refrigeration system having distributed intelligence control functions; the provision of such a distributed intelligence control for a refrigeration system which can operate in case of main controller failure; the provision of such a refrigeration system control which is capable of continuously monitoring the status of operating parameters of multiplexed compressors; the provision of such a commercial refrigeration system control which provides substantial information about compressor operating characteristics; the provision of such a refrigeration system control which is easy to assemble and install; the provision of such a refrigeration system control which operates control functions at low voltage; and the provision of such a refrigeration system which has simplified wiring.
Further among the several objects and features of the present invention may be noted the provision of a compressor safety and control module for a commercial refrigeration system which is capable of communicating compressor status information; the provision of such a compressor safety and control module which is capable of monitoring its own compressor""s operating parameters; the provision of such a compressor which shields sensors; the provision of such a compressor and compressor safety control module which provides highly accurate operating parameter data; the provision of such a compressor safety control module which can operate in cooperation with other compressor safety control modules if a master controller fails; the provision of such a compressor and compressor safety control module which is easy to wire into a refrigeration system.
Also among the objects and features of the present invention is the provision of a commercial refrigeration control system with increased system granularity. Such increase in granularity allows for closer matches of hardware to specific customer needs and requirements, with the need for little or no extemporaneous hardware. The provision of enhanced granularity also distributes the possibility of a failure over a wider hardware base, thereby limiting the severity of any potential adverse consequences to those functions contained within the failing device.
Further among the objects and features of the present invention is the provision of a commercial refrigeration control system that is easier to install and make operational than prior art systems. Such a system requires a minimum of power wiring and preferably allows subsystem components to receive power locally. Control is distributed over a low voltage communication channel so that high power signals are localized.
Generally, a commercial refrigeration system of the present invention suitable for use in a supermarket comprises an evaporator constructed and arranged to perform a cooling function. A compressor is in fluid communication with the evaporator for drawing refrigerant away from the evaporator. A condenser is in fluid communication with the compressor for receiving refrigerant from the compressor. The condenser is constructed and arranged for removing heat from the refrigerant. An expansion valve is in fluid communication with the condenser and receives refrigerant from the condenser. The expansion valve is constructed and arranged for delivering refrigerant into the evaporator. The system also includes a master controller. A compressor operating unit is associated with the compressor. The compressor operating unit is constructed and arranged for monitoring at least one operating parameter of the compressor and for determining whether the operating parameter is within specification. A first power and communication line extends from the master controller to the compressor operating unit and provides electrical power for the compressor operating unit. The master controller and compressor operating unit are constructed and arranged for digital communication over the power and communication line such that no separate power line for the operating unit must be wired upon installation of the system. A condenser fan is associated with the condenser and provides air cooling to remove heat from the refrigerant. A condenser controller is in digital communication with the master controller. The condenser controller is capable of providing a fan control signal. The condenser controller is constructed and arranged for monitoring at least one operating parameter of the condenser. A fan control unit associated with the condenser fan controls an operation of the condenser fan in response to the fan control signal. A second power and communication line extends from the condenser controller to the fan control unit and provides electrical power for the fan control unit. The system aslo includes an electronically controlled valve. A valve controller is in digital communication with the master controller. The valve controller is constructed and arranged for providing a valve control signal to the electronically controlled valve to position the electronically controlled valve at a desired setting in response to a valve control signal from the master controller. At least one branch control switch is constructed and arranged for controlling a flow of refrigerant. A branch controller is in digital communication with the master controller. The branch controller is constructed and arranged for providing at least one branch control signal to the at least one branch control switch in response to a branch control command from the master controller.
In another aspect, the present invention comprises a commercial refrigeration system suitable for use in a supermarket. The system includes an evaporator having a refrigerant selectively flowing therethrough to cool the evaporator. A compressor is in fluid communication with the evaporator and draws refrigerant away from the evaporator. A master controller selectively supplies a branch control signal. A power and communication line extends from the master controller. The system also includes a refrigeration branch comprising the evaporator, a refrigeration line for supplying the refrigerant to the evaporator, and a branch controller for controlling an operation of the refrigeration branch in response to the branch control signal. The master controller and branch controller are constructed and arranged for digital communication over the power and communication line such that no separate power line for the branch controller must be wired upon installation of the system.
In yet another aspect, the invention comprises a commercial refrigeration system suitable for use in a supermarket. The system includes an evaporator having a refrigerant selectively flowing therethrough for cooling the evaporator. A refrigeration line supplies the refrigerant to the evaporator. The evaporator and refrigeration line comprise a refrigeration branch. A compressor is in fluid communication with the evaporator. The compressor draws refrigerant away from the evaporator. A master controller selectively supplies a branch set point signal having a parameter representative of a desired characteristic of the refrigeration branch. A communication line extends from the master controller. A subsystem controller is in digital communication with the master controller over the communication line. The subsystem controller receives the branch set point signal and determines a branch control action in response thereto.
A further aspect of the invention comprises a commercial refrigeration system suitable for use in a supermarket. The system includes an electronically controlled valve. A master controller selectively supplies a valve control signal having a parameter representative of a desired position of the electronically controlled valve. A valve controller is responsive to the valve control signal and selectively supplies a valve drive signal to the electronically controlled valve. A communication channel extends from the master controller to the valve controller. The master controller supplies the valve control signal to the valve controller over the communication channel. The master controller and the valve controller are constructed and arranged such that no separate power line must be wired from the master controller to the valve controller upon installation of the system.
In yet another form, the invention comprises a commercial refrigeration system suitable for use in a supermarket. The system includes an electronically controlled valve having a plurality of valve positions. A master controller selectively supplies a set point signal having a parameter representative of a desired operating condition of the refrigeration system. A communication channel extends from the master controller. A valve controller is in digital communication with the master controller over the communication channel. The valve controller receives the set point signal over the communication channel and determines a valve drive signal as a function of the set point signal. The valve controller supplies the determined valve drive signal to the electronically controlled valve such that the desired refrigeration system operating condition is substantially achieved.
The invention further comprises a commercial refrigeration system suitable for use in a supermarket. Such a system includes at least one fixture. An evaporator is constructed and arranged for cooling the at least one fixture. A refrigerant supply line supplies a pressurized refrigerant to the evaporator. A master controller selectively supplies a fixture control signal having a parameter indicative of a desired fixture control action for the at least one fixture. At least one fixture sensor is associated with the at least one fixture. The at least one fixture sensor is constructed and arranged to provide a fixture status signal having a parameter representative of an operating condition associated with the at least one fixture. A communication channel extends from the master controller. A fixture controller is in digital communication with the master controller over the communication channel such that no separate power line must be wired from the master controller to the fixture controller upon installation of the system. The fixture controller receives the fixture control signal over the communication channel. The fixture controller is constructed and arranged for receiving the fixture status signal from the at least one fixture sensor and for supplying the fixture status signal to the master controller over the communication channel.
Yet another aspect of the present invention comprises a commercial refrigeration system suitable for use in a supermarket. The system includes at least one fixture. An evaporator is constructed and arranged for cooling the at least one fixture. A refrigerant supply line supplies a pressurized refrigerant to the evaporator. The system also includes a master controller and a fixture controller. At least one fixture sensor is associated with the at least one fixture. The at least one fixture sensor is constructed and arranged to provide a fixture status signal to the fixture controller. The fixture status signal has a parameter representative of an actual operating condition associated with the at least one fixture. A communication channel extends from the master controller to the fixture controller. The master controller selectively supplies a fixture set point signal to the fixture controller over the communication channel. The fixture set point signal has a parameter indicative of a desired operating set point for the at least one fixture. The fixture controller is responsive to the fixture set point signal for determining a fixture control action.
A further aspect of the present invention involves a commercial refrigeration system suitable for use in a supermarket. The system includes at least one fixture. An evaporator is constructed and arranged for cooling the at least one fixture. A refrigerant supply line supplies a pressurized refrigerant to the evaporator. The system also includes a master controller. At least one fixture sensor is associated with the at least one fixture. The at least one fixture sensor is constructed and arranged to provide a fixture status signal having a parameter representative of an operating condition associated with the at least one fixture. A communication channel extends from the master controller. A fixture controller is in digital communication with the master controller over the communication channel such that no separate power line must be wired from the master controller to the fixture controller upon installation of the system. The fixture controller is constructed and arranged for receiving the fixture status signal from the at least one fixture sensor and for supplying the fixture status signal to the master controller over the communication channel.
Yet another aspect of the present invention comprises a commercial refrigeration system suitable for use in a supermarket. The system comprises at least one fixture. An evaporator is constructed and arranged for cooling the at least one fixture. A refrigerant supply line supplies a pressurized refrigerant to the evaporator. The system also includes a master controller. A plurality fixture sensors are associated with the at least one fixture. The plurality of fixture sensors are constructed and arranged to provide a plurality of fixture status signals, with each of said plurality of fixture status signals having a parameter representative of an operating condition associated with the at least one fixture. A first communication channel extends from the master controller. A fixture controller is in digital communication with the master controller over the communication channel such that no separate power line must be wired from the master controller to the fixture controller upon installation of the system. A second communication channel extends from the plurality of fixture sensors to the fixture controller. The fixture controller being constructed and arranged for receiving the plurality of fixture status signals from the plurality of fixture sensors over the second communication channel and supplying the plurality of fixture status signals to the master controller over the first communication channel.
A further aspect of the present invention involves a method of installing a commercial refrigeration control system including a refrigeration subsystem, and a master controller providing a refrigeration set point control command to a subsystem controller controlling the refrigeration subsystem. The method comprises installing the master controller at a first location. The subsystem controller is installed at a second location. A source of electrical power is supplied to the master controller. A power and communication line is installed between the master controller and the subsystem controller whereby the refrigeration set point control command is provided over the power and communication line and no separate power line for the subsystem controller must be wired upon installation of the commercial refrigeration system.
Still another aspect of the present invention involves a method of installing a commercial refrigeration control system including a refrigeration subsystem, and a master controller providing a refrigeration set point control command to a subsystem controller controlling the refrigeration subsystem. The method includes installing the master controller at a first location. The subsystem controller is installed at a second location. A source of electrical power is supplied to the master controller. A communication channel is installed between the master controller and the subsystem controller. The master controller and said subsystem controller are constructed and arranged for digital communication over the communication channel such that the refrigeration set point control command is provided over the communication channel and no separate power wiring must be wired from the master controller to the subsystem controller upon installation of the commercial refrigeration system.
A further aspect of the present invention involves a commercial refrigeration system suitable for use in a supermarket. The system includes an evaporator constructed and arranged to perform a cooling function. A compressor is in fluid communication with the evaporator for drawing refrigerant vapor from the evaporator. A condenser is in fluid communication with the compressor for receiving refrigerant from the compressor. The condenser is constructed and arranged for removing heat to condense the refrigerant. An expansion valve is in fluid communication with the condenser for receiving liquid refrigerant from the condenser. The expansion valve is constructed and arranged for delivering refrigerant into the evaporator. A controller controls the compressor. A compressor operating unit is associated with the compressor. The operating unit is constructed and arranged for monitoring at least one operating parameter of the compressor and for determining whether the operating parameter is within specification. A power and communication line extends from the controller to the compressor operating unit and provides electrical power for the operating unit. The controller and compressor operating unit are constructed and arranged for digital communication over the power and communication line such that no separate power line for the operating unit must be wired upon installation of the system. The system also comprises a fixture for holding food. A secondary cooling loop is constructed and arranged for cooling the food in the fixture. The evaporator is in heat exchange relationship with the secondary cooling loop for removing heat therefrom.
Still another aspect of the present invention involves a method of controlling a commercial refrigeration system. The commercial refrigeration system comprises a master controller selectively supplying a master control signal, at least one subsystem controller selectively supplying a subsystem control signal, a communication channel extending between the master controller and the subsystem controller, and a controlled subsystem including a switching device having at least two operating states. The switching device is constructed and arranged to receive the subsystem control signal. The method comprises supplying the master control signal from the master controller to the at least one subsystem controller over the communication channel. The master control signal is received at the subsystem controller. The subsystem controller determines which one of the at least two operating states of the switching device corresponds to the master control signal. The subsystem controller outputs the subsystem control signal in a form that drives the switching device to the desired one of the at least two operating states whereby no separate communication channel exists between the master controller and the switching device.
These and still other objects and features of the present invention will become more apparent and in part pointed out hereinafter.